Wired: What might dolphins be saying with all those clicks and squeaks? Each other’s names, suggests a new study of the so-called signature whistles that dolphins use to identify themselves.
Whether the vocalizations should truly be considered names, and whether dolphins call to compatriots in a human-like manner, is contested among scientists, but the results reinforce the possibility. After all, to borrow the argot of animal behavior studies, people often greet friends by copying their individually distinctive vocal signatures.
“They use these when they want to reunite with a specific individual,” said biologist Stephanie King of Scotland’s University of St. Andrews. “It’s a friendly, affiliative sign.”
In their new study, published Feb. 19 in Proceedings of the Royal Society B, King and fellow St. Andrews biologist Vincent Janik investigate a phenomenon they first described in 2006: bottlenose dolphins recognizing the signature whistles of other dolphins they know.
Signature whistles are taught to dolphins by their mothers, and the results were soon popularized as evidence of dolphin names. Many questions remained, though, about the whistles’ function, and in particular about the tendency of dolphins to copy each others’ signatures.
Were they simply challenging each other, like birds matching each other’s songs in displays of territorial aggression? Or using the copied signals deceptively, perhaps allowing males to court females guarded by other males? Or was a more information-rich exchange occurring, a back-and-forth between animals who knew each other and were engaging in something like a dialog?
To investigate these possibilities, King and Janik’s team analyzed recordings made over several decades by the Sarasota Dolphin Research Program, a Florida-based monitoring project in which pairs of dolphins are captured and held in separate nets for a few hours as researchers photograph and study them.
During the captures, the dolphins can’t see each other, but can hear each other and continue to communicate. In their analysis, King and Janik showed that some of the communications are copies of captured compatriots’ signature whistles — and, crucially, that the dolphins most likely to make these were mothers and calves or closely allied males.
They seemed to be using the whistles to keep in touch with the dolphins they knew best, just as two friends might if suddenly and unexpectedly separated while walking down a street. Moreover, copying wasn’t exact, but involved modulations at the beginning and end of each call, perhaps allowing dolphins to communicate additional information, such as the copier’s own identity.
That possibility hints at what linguists call referential communication with learned signals, or the use of learned rather than instinctively understood sounds to mentally represent other objects and individuals. As of now, only humans are known to do this naturally. [Continue reading…]
The reluctance to posit human traits in animals — for fear that one might be anthropomorphizing what are intrinsically non-human behaviors — is itself the expression of a prevailing anthropocentric superstition: that human beings are fundamentally different from all other animals.
When it comes to discerning human-like communication in non-human species there is an additional bias: scientific researchers tend to over-emphasize the function language has as a system of symbolic representation and understate its importance as a means for engaging in emotional exchanges.
Even though our understanding of dolphin communication is very rudimentary, I’d be inclined to believe not only that dolphins do call each other by name, but that they are also keenly attuned and adept in the combination of name and tone.
After all, the utterance of an individual’s name generally signifies much less than the way the name is called — unless that is one is sitting in a waiting room and being hailed by a nameless official. Lucky for dolphins their exchanges never need to be straight-jacketed like that.